Relative value of bedside screening tests of difficult intubation
| Screening tests of difficult intubation | Non-difficult intubation (n=1733) | Difficult intubation (n=276) | P value | Sensitivity (%, 95% CI) | Specificity (%, 95% CI) | Positive predictive value (%, 95% CI) | Negative predictive value (%, 95% CI) | ROC area (95% CI) |
| Upper airway obstruction, n (%) | 61 (4) | 28 (10) | <0.001 | 10 (7 to 14) | 97 (96 to 97) | 32 (22 to 42) | 87 (86 to 89) | 0.53 (0.52 to 0.55) |
| Known prior history of difficult airway | 150 (9) | 41 (15) | 0.001 | 15 (11 to 20) | 91 (90.9 to 93) | 22 (16 to 28) | 87 (85 to 88) | 0.53 (0.51 to 0.55) |
| Micrognathia | 27 (2) | 12 (4) | 0.002 | 4 (2 to 8) | 98 (98 to 99) | 31 (17 to 48) | 87 (85 to 88) | 0.51 (0.5 to 0.53) |
| Limited mouth opening | 262 (15) | 60 (21) | 0.005 | 15 (14 to 17) | 78 (73 to 83) | 13 (11 to 15) | 81 (77 to 86) | 0.47 (0.44 to 0.49) |
| Limited neck extension | 27 (2) | 10 (4) | 0.02 | 4 (2 to 7) | 98 (98 to 99) | 27 (14 to 44) | 87 (85 to 88) | 0. 51 (0.49, 0.52) |
| Cleft palate | 17 (1) | 7 (3) | 0.03 | 3 (1 to 5) | 99 (98, 99.) | 29 (13 to 51) | 86 (85 to 88) | 0.51 (0.49 to 0.52) |
| Midfacial hypoplasia | 10 (<1) | 4 (1) | 0.1 | 2 (0.4 to 4) | 99 (98 to 99) | 29 (8 to 58) | 86 (85 to 88) | 0.5 (0.49 to 0.51) |
| Short thyromental distance | 250 (14) | 43 (16) | 0.6 | 14 (13 to 16) | 84 (80 to 88) | 14 (12 to 15) | 85 (81 to 89) | 0.49 (0.47 to 0.52) |
ROC, receiver operator curve.